The present invention relates to an assembly of a pneumatic tire and a rim in which a noise damper made of sponge material is disposed in a tire cavity, thereby reducing a road noise during running.
To reduce a road noise during running, Japanese Examined Patent Application Publication No. 3612059 and Japanese Published Patent Application No. 2005-138760 propose to dispose a noise damper comprising a long band-like sponge material extending in a circumferential direction of a tire in a tire cavity. Thereby, energy of resonance vibration of air (cavity resonance) of air generated in the tire cavity can be absorbed and moderated by the noise damper.
The noise damper is formed by fixing a bottom surface of the noise damper to a cavity surface on the side of the tire or on the side of the rim. This prevents the noise damper from moving in the tire cavity and rubbing against the tire cavity surface, prevents the noise dampers from rubbing against each other, and prevents the tire and the noise damper from being damaged.
In the noise damper, a stress acting during running is prone to concentrate on an outer end of a fixing surface (bottom surface) in the circumferential direction of the tire. Therefore, there is a tendency that a crack and damage are prone to be generated in the sponge material in the vicinity of the outer end of the fixing surface.
As an output of a vehicle is improved and the length of the expressway is increased, there is a tendency that the average running speed of vehicles is also increased, and a large force is prone to be applied to a noise damper fixed to a cavity surface of a tire. Especially, external forces in various directions are applied to the noise damper when the vehicle runs, brakes and/or turns. Therefore, in the case of a pneumatic tire having such a noise damper, it is necessary to enhance the durability of the noise damper so that it can withstand a long term use.
In an assembly of a tire and a rim having a noise damper, it is necessary to reduce a stress concentration at outer ends and corners of various parts of the noise damper and to enhance the durability without deteriorating the road noise reducing effect.
In the noise damper a (symbols are shown in FIG. 10), to enhance the adhering operation efficiency to a tire, when the noise damper a is to be produced, a double-faced tape is pasted on a bottom surface as in some cases. However, when the noise damper a to which the double-faced tape is pasted is packed in a box and transported from a producing factory to a tire producing factory, the noise damper a is deviated in position in the box by vibration and acceleration at the time of transportation. Further, the outer end e (the end of the length direction) is prone to collide against a wall surface of the box. At that time, a double-faced tape at the outer end is crushed, the double-faced tapes are adhered to each other, a peeling off paper is peeled off and the adhering surface is deteriorated and the adhering strength is deteriorated.
As a result, when a tire to which such a noise damper a is adhered is used, the adhered portion of the noise damper a is peeled off from the tire, starting at the outer end b. Thus, there is a problem that the durability of the noise damper and the durability of the tire are deteriorated. Also, an outer appearance of the tire is also deteriorated.
It is necessary to reduce a mass of at least one of the outer ends ae of the noise damper, to reduce a stress applied to the fixing surface, and to suppress the crack or damage. Thus, as shown in FIG. 10, the Japanese Published Patent Application No. 2005-138760 proposed that both outer ends ae of the noise damper a in the circumferential direction of the tire are formed into inclined surface portions having acute tip ends.